The overall goal of the proposed research is to determine those mechanisms which permit follicles to ovulate in response to LH. Steroids and prostaglanding have both been implicated as mediators of LH induction of the ovulatory process. However, neither LH, steriods nor prostaglandins alone stimulate ovulation. Therefore, the specific aims of the proposed research are: 1) Determine the effects of LH on follicular androgen synthesis in developing preovulatory follicles and during early luteinization; 2) Determine the effects of hormones on production of prostaglandins by cells of small antral and preovulatory follicles; and 3) Determine some of the mechanisms by which the preovulatory follicle ruptures and reorganizes itself into a corpus lutem. Results of these proposed projects should determine in what cell type (granulosa or theca) and by what mechanism LH, steroids and prostaglandins interact to allow the ovulatory process to occur. Particular emphasis will be placed on examining theca cell steroidogenesis and the production and action of prostaglandins in follicles and different stages of development. Further, the third specific aim should delineate the intrafollicular localization of types I, III and IV collagen, lamenin and fibronectin and demonstrate at which stage of follicular growth collagenase activity can be induced and by which hormones. By unravelling the intrafollicular control of prostaglandin synthesis and action as well as of collagenase activity, LH control of ovulation should begin to be elucidated.